The invention relates to a apparatus for checking the accuracy of a circular path of a machine tool performed by a work spindle and/or a machine table, in particular an NC-controlled machine tool, with a clamping element coaxially attached on the work spindle, a first rotary bearing attachable to the clamping element with a rotation axis coaxial to the work spindle and an orthogonal pivot axis for a first pivot bearing, a measurement arm having the pivot bearing, an adjusting device receiving the measurement arm with a second pivot bearing having a pivot axis parallel to the pivot axis of the first pivot bearing, a second rotary bearing with a rotation axis oriented parallel to the work spindle, and a stator supporting the second rotary bearing, wherein a length measurement system for determining a radial deviation of the work spindle from a circular path is provided in the measurement arm.
It would therefore be desirable and advantageous to provide an improved apparatus to obviate prior art shortcomings and to perform more precise measurements.